project_root is a string not a Path instance
project_root is a string not a Path instance

Summary:
The project_root variable in buck.py is a string (sourced from the
command line options), but the tests supply a faked Path object instead. This
can break alternative glob implementations that expect a string here.

Test Plan: Run `ant test` and `buck test`.

Reviewed By: bhamiltoncx

fbshipit-source-id: 53a5293

LegNeato/buck,shs96c/buck,daedric/buck,davido/buck,justinmuller/buck,brettwooldridge/buck,robbertvanginkel/buck,zhan-xiong/buck,justinmuller/buck,SeleniumHQ/buck,zpao/buck,zhan-xiong/buck,JoelMarcey/buck,shs96c/buck,SeleniumHQ/buck,ilya-klyuchnikov/buck,brettwooldridge/buck,clonetwin26/buck,shybovycha/buck,SeleniumHQ/buck,rmaz/buck,grumpyjames/buck,zpao/buck,facebook/buck,romanoid/buck,grumpyjames/buck,k21/buck,LegNeato/buck,zpao/buck,zhan-xiong/buck,romanoid/buck,marcinkwiatkowski/buck,marcinkwiatkowski/buck,vschs007/buck,ilya-klyuchnikov/buck,sdwilsh/buck,zhan-xiong/buck,rmaz/buck,Addepar/buck,rmaz/buck,facebook/buck,marcinkwiatkowski/buck,romanoid/buck,ilya-klyuchnikov/buck,vschs007/buck,JoelMarcey/buck,SeleniumHQ/buck,sdwilsh/buck,illicitonion/buck,zpao/buck,justinmuller/buck,robbertvanginkel/buck,clonetwin26/buck,sdwilsh/buck,daedric/buck,clonetwin26/buck,zhan-xiong/buck,vschs007/buck,romanoid/buck,robbertvanginkel/buck,SeleniumHQ/buck,davido/buck,k21/buck,nguyentruongtho/buck,romanoid/buck,Addepar/buck,clonetwin26/buck,romanoid/buck,facebook/buck,darkforestzero/buck,dsyang/buck,ilya-klyuchnikov/buck,grumpyjames/buck,vschs007/buck,rmaz/buck,brettwooldridge/buck,LegNeato/buck,zhan-xiong/buck,illicitonion/buck,rmaz/buck,LegNeato/buck,shs96c/buck,brettwooldridge/buck,brettwooldridge/buck,clonetwin26/buck,daedric/buck,darkforestzero/buck,illicitonion/buck,shs96c/buck,JoelMarcey/buck,nguyentruongtho/buck,LegNeato/buck,rmaz/buck,marcinkwiatkowski/buck,illicitonion/buck,darkforestzero/buck,clonetwin26/buck,daedric/buck,ilya-klyuchnikov/buck,brettwooldridge/buck,brettwooldridge/buck,shybovycha/buck,dsyang/buck,illicitonion/buck,rmaz/buck,SeleniumHQ/buck,grumpyjames/buck,darkforestzero/buck,SeleniumHQ/buck,darkforestzero/buck,shybovycha/buck,nguyentruongtho/buck,sdwilsh/buck,dsyang/buck,shs96c/buck,SeleniumHQ/buck,romanoid/buck,sdwilsh/buck,Addepar/buck,dsyang/buck,daedric/buck,JoelMarcey/buck,shybovycha/buck,kageiit/buck,LegNeato/buck,Addepar/buck,grumpyjames/buck,brettwooldridge/buck,davido/buck,shybovycha/buck,justinmuller/buck,justinmuller/buck,justinmuller/buck,kageiit/buck,romanoid/buck,k21/buck,nguyentruongtho/buck,kageiit/buck,vschs007/buck,marcinkwiatkowski/buck,shybovycha/buck,clonetwin26/buck,daedric/buck,sdwilsh/buck,Addepar/buck,daedric/buck,zpao/buck,davido/buck,romanoid/buck,sdwilsh/buck,davido/buck,grumpyjames/buck,clonetwin26/buck,grumpyjames/buck,shybovycha/buck,k21/buck,robbertvanginkel/buck,ilya-klyuchnikov/buck,k21/buck,zhan-xiong/buck,nguyentruongtho/buck,shybovycha/buck,shybovycha/buck,k21/buck,illicitonion/buck,shs96c/buck,illicitonion/buck,robbertvanginkel/buck,vschs007/buck,dsyang/buck,LegNeato/buck,grumpyjames/buck,facebook/buck,grumpyjames/buck,zhan-xiong/buck,daedric/buck,zhan-xiong/buck,sdwilsh/buck,romanoid/buck,sdwilsh/buck,davido/buck,daedric/buck,daedric/buck,davido/buck,kageiit/buck,justinmuller/buck,kageiit/buck,zhan-xiong/buck,vschs007/buck,shybovycha/buck,Addepar/buck,k21/buck,grumpyjames/buck,davido/buck,ilya-klyuchnikov/buck,davido/buck,LegNeato/buck,Addepar/buck,darkforestzero/buck,ilya-klyuchnikov/buck,vschs007/buck,shs96c/buck,vschs007/buck,marcinkwiatkowski/buck,marcinkwiatkowski/buck,ilya-klyuchnikov/buck,robbertvanginkel/buck,brettwooldridge/buck,k21/buck,davido/buck,marcinkwiatkowski/buck,romanoid/buck,ilya-klyuchnikov/buck,JoelMarcey/buck,Addepar/buck,justinmuller/buck,vschs007/buck,Addepar/buck,shs96c/buck,davido/buck,facebook/buck,SeleniumHQ/buck,dsyang/buck,vschs007/buck,robbertvanginkel/buck,justinmuller/buck,rmaz/buck,marcinkwiatkowski/buck,SeleniumHQ/buck,nguyentruongtho/buck,darkforestzero/buck,robbertvanginkel/buck,romanoid/buck,dsyang/buck,Addepar/buck,brettwooldridge/buck,darkforestzero/buck,Addepar/buck,sdwilsh/buck,clonetwin26/buck,k21/buck,kageiit/buck,shs96c/buck,illicitonion/buck,davido/buck,illicitonion/buck,LegNeato/buck,zpao/buck,davido/buck,clonetwin26/buck,ilya-klyuchnikov/buck,JoelMarcey/buck,justinmuller/buck,shybovycha/buck,clonetwin26/buck,SeleniumHQ/buck,daedric/buck,marcinkwiatkowski/buck,zhan-xiong/buck,JoelMarcey/buck,rmaz/buck,justinmuller/buck,dsyang/buck,JoelMarcey/buck,justinmuller/buck,k21/buck,sdwilsh/buck,shs96c/buck,JoelMarcey/buck,brettwooldridge/buck,Addepar/buck,sdwilsh/buck,robbertvanginkel/buck,shybovycha/buck,marcinkwiatkowski/buck,k21/buck,ilya-klyuchnikov/buck,marcinkwiatkowski/buck,shs96c/buck,ilya-klyuchnikov/buck,grumpyjames/buck,robbertvanginkel/buck,illicitonion/buck,rmaz/buck,dsyang/buck,LegNeato/buck,robbertvanginkel/buck,clonetwin26/buck,daedric/buck,sdwilsh/buck,SeleniumHQ/buck,dsyang/buck,robbertvanginkel/buck,illicitonion/buck,marcinkwiatkowski/buck,dsyang/buck,illicitonion/buck,clonetwin26/buck,zhan-xiong/buck,robbertvanginkel/buck,kageiit/buck,JoelMarcey/buck,brettwooldridge/buck,shs96c/buck,facebook/buck,daedric/buck,darkforestzero/buck,romanoid/buck,Addepar/buck,vschs007/buck,JoelMarcey/buck,rmaz/buck,zpao/buck,SeleniumHQ/buck,zhan-xiong/buck,LegNeato/buck,facebook/buck,rmaz/buck,LegNeato/buck,vschs007/buck,justinmuller/buck,darkforestzero/buck,k21/buck,darkforestzero/buck,darkforestzero/buck,shybovycha/buck,nguyentruongtho/buck,k21/buck,grumpyjames/buck,dsyang/buck,shs96c/buck,JoelMarcey/buck,brettwooldridge/buck,darkforestzero/buck,dsyang/buck,LegNeato/buck,rmaz/buck,JoelMarcey/buck,illicitonion/buck